1. Technical Field of the Invention
This invention relates to a clutch and more particularly a system for remotely adjusting and locking up a friction clutch.
2. Description of Prior Art
Friction clutches that engage at a predetermined speed have been known for some time and are particularly useful in combination with motors, such as internal combustion engines, that are not capable of starting under load conditions. The engine is permitted to accelerate freely with the clutch disengaged until a point on the power curve is achieved where the engine produces sufficient torque. At this predetermined speed the clutch automatically engages to transfer the torque.
Previously known centrifugal friction clutches have exhibited a number of important shortcomings. U.S. Pat. No. 4,111,291 discloses a centrifugally actuated friction clutch, designed for a small displacement internal combustion engine, connected to the rear axle of a go-cart. This clutch uses centrifugal force to transmit the engine's torque to the wheels. Spring force in the clutch is adjusted to counteract the engagement by centrifugal force until the engine reaches a predetermined speed. Then the clutch hooks up and stays hooked up until the engine drops below this predetermined speed. The '291 patent discloses a plurality of screws for adjusting the spring force that are accessible through apertures in the clutch cover to allow adjustment without disassembling the clutch. This accessibility, while allowing fine adjustment of the engagement speed by trial and error of on-track testing, still requires that the go-cart be taken off the track and stopped so that a screw driver may be inserted into the apertures to make the required adjustments.
This prior art clutch is undesirable because of (1) the consumption of time required for an empirical analysis to achieve the right adjustment for different track conditions; (2) inability of the operator to have immediate feedback of the operation of the clutch while the vehicle is moving; and (3) lack of an engagable and disengagable lockup mechanism to provide enhanced engagement of the friction clutch while the vehicle is moving.